Television system



L. W. KOLOZSY TELEVISION SYSTEM 2 Sheets-Sheet 1 7 Filed April 26,) 1935INVENTOR. 1011/; W. haLozsy ATTORNEY.

L. w. KOLOZSY TELEVI5 ION SYSTEM Filed April 26, 1935 L 2 Sheets-Sheet 2INVENTOR. [00/5 W #04025) ATTORNEY.

jam. .17, 1939.

Patented Jan. 17, 1939 UNITED STATES PATENT OFFIQE TELEVISION SYSTEMApplication April 26,

12 Claims.

This invention relates to the electrical transmission of pictures andimages and more particularly to the electrical transmission of picturesor images at a relatively high rate of speed, commonly known astelevision. My invention is particularly concerned with apparatus foruse at the receiving end of such systems, and for the purpose of thisspecification it will be assumed that there is available a signaltransmitted according to any known system and representing the lightintensities of successive elemental areas of the image to be reproduced,derived by scanning the subject in a series of straight lines in onedirection, each successive line being slightly displaced at right anglesto the direction of the line. I have assumed also that it is desired toproduce twenty-four pictures per second of 240 lines each, but it willbe understood that this is merely by way of example and for purposes ofsimplicity in explaining my invention, and that different numbers ofpictures may be transmitted per second or a different number of linesper picture.

In general, television receiving systems such as heretofore proposedfall into two classes, the mechanical scanning system, and the cathoderay or electrical scanning system. Each of these two classes has certainadvantages and disadvantages and neither of them as at presentconstituted is, in my opinion, completely satisfactory.

The cathode ray system is regarded by many as having advantages ofsimplicity and less mechanical complications, but it has other defectswhich have so far detracted from its usefulness. Among the difficultiesof this type of system may be mentioned that of obtaining a picturelarge enough to be viewed by a fairly good sized audience. Even picturesas small as eight inches square are difficult to obtain with a cathoderay system, since the cost of the tubes, as new constructed, even forthis relatively small size, is prohibitive.

It has been suggested to magnify an image produced by a cathode ray tubeby means of a lens, but this has not proved to be practical because theangle through which the audience may view the picture is relativelysmall unless the lens is made extremely large. For a fairly good sizedaudience a field angle of horizontally is desirable and at least 15vertically.

In accordance with my invention I may utilize a cathode ray tube of newand improved construction and by control of the travel of the electronbeam scan the screen in one direction and also vary the light intensity,but an ordi- 1935, Serial No. 18,304

nary cathode ray tube may be used, and modulated by any conventionalmeans. I scan the screen in the other direction by means of a system ofrotating mirrors providing a wide angle of view. The desired wide angleand magnification horizontally is afforded by the rotating mirrors. Thevertical magnification in which the angle of the field of view isconsiderably smaller, may be provided by a lens and proper dispositionof the screen of the tube.

In accordance with my invention I prefer to utilize a cathode ray toprovide a vertical line of light traced by the moving luminous spot, theintensity of which is controlled as will be explained hereinafter, and Iproject this vertical line of light upon a series of closely spaced,vertically mounted, triangular mirror assemblies mounted side by sideand arranged each for rotation about its own vertical axis.

The angle of the face vertical mirrors with respect to the plane of thescreen and with respect to each other is so chosen together with therate of speed of rotation of the mirrors, that upon rotation thevertical line of light appears at the extreme edge of the screen, saythe left hand edge as the audience views it, and progressively travelsacross the first mirror to its right hand edge; thence on to the lefthand edge of the second mirror; thence across the second mirror to itsright hand edge; thence to the left hand edge of the third mirror, andso on progressively until it has completely crossed the screen, at whichtime the next line appears at the left hand edge of the screen andlikewise travels across it, the whole process, of course, beingsufficiently rapid so that the desired number of complete pictures persecond are presented.

Among the objects of my invention are:

To provide an improved television receiving system capable of producingpictures of satisfactory detail and of considerably larger effectivesize than can be produced by known cathode ray systems and to avoidobjectionable flickering of the pictures.

To provide new and improved forms of cathode ray tubes particularlyadapted for use with my invention.

To provide new and improved rotary mirror systems particularly adaptedfor use with my invention.

To provide means for converting the uniform rotation of the prime moverof the mirror system into a cyclically varying speed of rotation.

To provide new and improved electrical circuits for controlling theintensity of the illumination.

To provide cathode ray tubes giving a greater effective illuminationthan has been heretofore possible.

To provide a new and improved cathode ray tube capable of producing inmy system a larger picture than heretofore while reducing the cost andcomplexity and the manufacturing difficulties of producing the cathoderay tubes.

Still other objects and advantages of my invention will be apparent fromthe specification.

The features of novelty which I believe to be characteristic of myinvention are set forth with particularity in the appended claims. Myinvention itself, however, both as to its fundamental principles and asto its particular embodiments will best be understood by reference tothe specification and accompanying drawings, in which Fig. l is adiagrammatic perspective View of a projector and receiving screen inaccordance with my invention;

Figs. 2 and 3 are respectively front and side elevations, partly insection, of the projector according to my invention;

Fig. 4 is a diagrammatic plan view of the rotating mirror receivingscreen in accordance with my invention;

Fig. 5 is a sectional elevation of a single mirror and its mounting asused in my receiving screen;

Fig. 6 is a diagrammatic view of a detail of the mirror speed controlmechanism; and

Fig. 7 is a series of curves showing the relation between the speed ofthe prime mover and the speed of the mirror.

Referring now more particularly to Fig. 1, l0 designates generically theprojector in which there is mounted the cathode ray tube II. The lightfrom this cathode ray tube H is projected upwardly and falls upon themirror or prism 52 which serves to direct it at right angles through thelens l3, which is preferably a, cylindrical lens arranged with its axishorizontal to give vertical magnification and to have substantially noeifect horizontally. The light is projected upon the receiving screen21, mounted on the cabinet 29, within which there may be provided thenecessary receiving, amplifying and control apparatus; connections, notshown in Fig. 1, being provided between the receiver cabinet 20 and theprojector Ill.

Assuming that the tube H produces in the projector head a vertical lineof light as indicated in Fig. 2 (this being made up of a traveling spottraveling vertically but not horizontally), it will be seen that thisline of light will be projected upon the screen.

The receiving screen is shown diagrammatically in Fig. 4, the view beinga plan View. The screen is made up of a series of rotatable,triangularly arranged mirror assemblies, in this instance twelve beingindicated by the numerals 22 to 33, the vertical axes thereof beinglaterally aligned in the plane of the receiving screen. As will be seen,each of the mirror assemblies is, in horizontal section, in the form ofan equilateral triangle, and each face thereof is approximately one inchin width. Vertically, the mirrors are whatever height of screen thesystem is designed for.

As will be noted from Fig. 4 the mirror assemblies are so mounted thatthe corresponding faces thereof are displaced 10 in a counterclockwisedirection, reading from left to right, when the mirror set is standingstill. This will be seen by comparing the positions of the faces 22a to33a inclusive.

All the mirror assemblies 22 to 33 are rotated simultaneously in thesame direction, 1. e., clockwise, and at the same rate of speed, by acommon drive shaft 44 through worm gears 43, as

will be more fully hereinafter described.

In understanding the operation of this mirror system it will beappreciated that the full action takes place extremely rapidly when itis considered that 24 pictures, composed of a total of 5,760 lines,traverse the entire screen in each second. The action is, therefore,imperceptible to the naked eye in the detail in which it will beanalyzed now.

The first step to understand is the movement of the picture lines oflight across the screen to give the desired horizontal spreading ormagnfication. For this purpose the action will be described withreference to a single picture line of light. It is known that if a lineis reflected in a mirror, and the mirror is rotated on its verticalaxis, as in a clock-wise direction, that line of light will appear tomove across the mirror toward the right, thus giving the effect ofspreading the line of light if the action is fast enough to gain theeffect through the persistence of vision.

Applying this phenomena to the present apparatus, and considering thatthe front of the screen is toward the bottom of Fig. 4, the line oflight from the lens I3 will appear to an observer upon the face a ofmirror 22. As this mirror is rotated in a clock-wise direction, the lineof light will appear to move across the face a of the mirror 22 towardthe mirror 23. By the time the mirror 22a reaches a position where itsfurther movement will render it no longer effective to reflect the lineof light to the ob server, the line appears at the extreme right handedge of mirror 22a, but by that time the mirror 23a has rotated so as tobe in position (shown by dotted line A) to pick up the line of light,which 5 it does as the rotation of the mirrors continues.

As mirror 23a rotates, the line of light again appears to move to theobservers right and, as mirror 23a is about to become ineffective torefiect the same to the observer, mirror 24a is then in position to pickup the line, which it does. Thus, the line of light forming the picturetraverses the screen from the observers left toward the right, and byreason of the rapidity of the action and the persistence of vision, thedesired horizontal spreading is obtained.

It will be understood by those skilled in the art that the picture ismade up of what appears to be 240 lines formed bythe movement of thespot of light from the cathode ray tube in correspondence to theoperation of the scanning apparatus. In this instance, the movement isvertically from the top of the screen to the bottom thereof so that thelines appear vertical.

Inasmuch as there are thirty-six mirrors, 22a

to 330, and the mirror assemblies 22 to 33 rotate eight times persecond, each mirror surface reflects twenty picture lines during eachinterval that it is effective, or one-twelfth of the picture, and eachline is of varying intensity in agreement with the particular portion ofthe picture being scanned. The rapidity with which the projected line oflight moves across each mirror and from mirror to mirror is sufiicientlyfast that the entire picture appears to the observer to fill the wholescreen.

By the time the traversal is completed across mirror 33a, then mirror22b is in position to reflect the first of the lines of the succeedingpicture, and the action will pass from mirror 22b to mirror 23b tomirror 24?), and so on, across the screen as described above. Whenmirror 33b is no longer effective, mirror 220 is then in position toreflect the lines of the following picture, which traverses the screenin the same manner; and so the action continues so as to reproduce 24pictures upon the complete screen in each second.

From the foregoing description it will be appreciated that using twelvemirrors for the screen, each mirror is displaced 10 with respect to theother because the two side edges of any mirror face are spacedcircumferentially 120 apart and at all times, no matter from whatdirection the screen is being observed, there will. be a continuity ofreflecting surface or screen to the observer.

The second step to understand in the operation of the mirrors is that ithas been found experimentally that a mirror of the width given in thisspecification is effective to reflect an image to an observer during amovement of approximately 1 However. from the foregoing description. itwill be seen that. if no compensating mechanism were provided. each ofthe 12 mirrors rotates a total of 10 during the time that its lightreflecting surface is toward the observer. and a total of 120 in orderto bring the following mirror face of its assembly into reflectingposition. If the twelve mirrors were spaced apart circumferentially thissmall distance. then with. twelve mirrors there would be total movementf 18 with the result that until the mirror assemblies rotated theremainin 102 of the 120 m vement required. there would be a time elem ntduring which no mirror would be in light reflecting os tion and hencethe continuity of action would be interrupted and the apparatus would otbe practical.

Accordingly, I provide means for retarding the rotation of the m rrorduring the time embracin its 1 /9" movement referred to above. and toancelerate the rotation of each m rror durin the remainder of itsoperatin movement. Again. t will be understood that this acceleratedaction occurs while the persistance of vision is ma ntaining thepicture. and without pass ng the m rror throu h a light reflectingposition. so that it is unnoticed by the naked eve.

Referr ng now more particularly to Fi 5. 22 represents the mirrorassembly which is made hollow and preferably in the shape of a bottle.as indicated. having a reduced rounded lower portion or neck. The mirrorassembl s ca ried upon shaft and its upper end only is secured to theshaft by means of a disk 36. The upper end of shaft 35 is preferablymounted in a suitable bearing diagrammatrically indicated at 3B and itslower end may be mounted in bearing 39. The shaft 35 may carry a wormwheel 43 enga ing worm 34 driven from the prime mover. The lower neckportion of the mirror assembly may be mounted in suitable bearing 3! andI preferably provide at the lower extremity of the mirror assembly atriangular piece of magnetic material such as iron 4E} having its apexesrounded off and juxtapositioned to magnetic pole piece 4|, that isprovided with the magnetizing coil 42, as shown in detail in Fig. 6. Thecoil 52, being supplied with constant direct current, sets up a steadyflux in pole piece 4| passing into the iron triangle 4B.

As one of the apexes of armature begins to approach the pole piece 4i,as will be understood, there is developed a force tending to acceleratethe rotation of the piece til, and with it the mirror to which it issecured. After the apex passes across the face of the pole piece 4| andbegins to move away from it, this force introduces a drag tending toslow down the rotation of the mirror.

After the apex has passed off the pole piece 4| and substantially out ofits zone of attraction, there will be no effect until the nextsucceeding apex has passed into the zone of attraction, when the sameforces are again produced.

Thus it will be seen that three times during each complete revolution ofthe mirror assembly it receives an accelerating impulse and three timesin each revolution a decelerating impulse, the magnitude of which may becontrolled by the current through coil A2 or the position of the polepiece 4! and the time between the accelerating and decelerating impulsesmay be controlled by the width of the pole piece.

The phase of the impulses can of course be varied by changing therelative locations of the pole piece M and the armature 49.

The shaft 35 has torsional elasticity and the mirror 22 has relativelyli.tt1e,.but has considerable mass, so that the system acts as amechanical vibrator and can be set and is set into mechanical vibrationat resonance which is the natural period of the shaft and its mirrorassembly by the continued accelerating and decelerating impulses, theeffect of which is shown by Fig. 7.

If the mirror were not rotated about its own axis but were set intovibration as by being given a twist, the mirror would continue tovibrate or oscillate torsionally, rotating clockwise, for example,through a small angle coming to rest. then rotating counterclockwisethrough a similar angle, coming to rest and continuing to oscillatetorsionally on the shaft as an axis. in the manner of a torsionalpendulum. Its angular velocity might then be represented by curve A ofFig. 7. a sine wave whose axis is zero. Such an. arrangement would notfunction satisfactorily in my sys tem due to the re-reflection of theimage as the mirror oscillated through its reflecting position. Hence Iadd the element of constant rotation.

Torsional vibration is not interfered with by the rotation of the shaft35, supporting the mirror, at a constant rate of speed. which force isindicated by the dotted line B of Fig. 7, and the resultant angularvelocity of the mirror in my system is given by the sun of the twomotions, indicated in this instance by the full line curve C in whichthe angular velocity increases and decreases periodically also as a.sine wave. By choosing the amount of torsional vibration and itsvelocity it will be seen that the mirror may be made to accelerateperiodically over the constant velocity which it would otherwise have,and may be retarded to the degree desired.

The apparatus is so designed that the natural period of vibration orresonance of the shaft 35 and its mirror assembly is twenty-four persecond. While it is only necessary to slow up the rotation of a mirrorduring of a second in which time the mirror moves one and one-halfdegrees, the mechanism here provided slows up the rotation duringapproximately one-half of its rotative movement for one picture andaccelerates the rotation during the other half. In point of time, thedeceleration and acceleration each lasts about one forty-eighth of asecond.

With the parts proportioned and arranged as above described, the mirrorassemblies rotate at the rate of eight revolutions per second, which isa slow speed for elements one inch or thereabout in width, wherebylittle noise or vibration is produced.

With this rotating mirror screen the aspect ratio of the picture wouldchange, with a change in distance between the observer and screen, sincean observer near it will see a narrower picture than an observer fartheraway, but this diffi culty, however, may be overcome by properproportioning of the lens in the projector, since magnifying lensesincrease their magnification the greater the distance at which they areviewed. It is preferable to provide a lens with a focal length of in theexample hereinbefore described, and the cathode ray screen is placedthree-quarters of the focal length away from the lens, and the distancefrom the projector to the mirror screen is about six feet. If theobservers are approximately the same distance from the screen as theprojector, then the increase of magnification caused by the lens willequal the increase of the magnification caused by the vertical mirrorsand within observing limits of four to eight feet from the screen thevertical dimension of the picture will increase equally with thehorizontal dimension, and the aspect ratio of the picture will notnoticeably change as the observer moves within the limit.

The same result might be obtained by the use of a cylindrical, concavelens placed in front of the screen, the effect of which would be todecrease the width of the picture with increasing observing distance andso to neutralize the above mentioned phenomena This method of equalizingthe aspect ratio is, however, not as desirable as the former.

While I have shown and described certain preferred embodiments of myinvention by way of example, it will be understood that modificationsand changes may be made within the spirit and scope of my invention, aswill be understood by those skilled in the art.

For example, the mirrors may be wider and longer, with correspondingchanges in projecting apparatus and effective degrees of movement ofeach mirror. Also, with changes in the number of lines comprising apicture the number of mirror assemblies may be'varied with acorresponding proportioning of the speed of rotation of each, etc., forwhich purpose the foregoing example will serve as a guide.

I claim:

1. In a television receiver, in combination, a multiplicity of mirrorassemblies, each mounted for rotation on its own vertical axis, with thevertical axes of the several mirror elements defining the plane of thescreen, means for rotating the mirror assemblies, whereby the linesforming the picture may be spread horizontally, and means for projectinga vertically moving light spot upon said screen.

2. In a television receiver, in combination, a multiplicity of' mirrorassemblies, each mounted for rotation about its own axis, with the axesof the several mirror elements defining the plane of the screen, meansfor rotating the mirror assemblies, whereby the picture may bereproduced in one direction, and means for projecting upon said screen aspot of light moving in the direction of the said axes, whereby thepicture may be reproduced in a second direction.

3. In a television receiver, in combination, a multiplicity of mirrorassemblies, each mounted for rotation about its own axis, with the axesof the several mirror elements defining the plane of the screen, meansfor rotating the mirror assemblies, a cathode ray tube arranged toproduce by movement of the electron beam a swinging spot of light, andmeans for projecting said swinging spot upon said screen in such amanner that movement of said spot traces a line of light on the mirrorparallel to its axis.

4. A television receiver screen comprising, in combination, amultiplicity of mirror assemblies each mounted for rotation about itsown axis with the axes of the several mirrors defining the plane of thescreen, and each mirror assembly having at least three angularlydisposed mirror faces, and means for rotating the mirror assemblies.

5. A television receiver screen comprising, in combination, amultiplicity of mirror assemblies each mounted for rotation about itsown axis and with the several axes defining the plane of the screen,means for rotating all of said mirrors in synchronism, and meansassociated with each mirror assembly for cyclically increasing anddecreasing the speed of rotation of each mirror independently.

6. A television receiver screen comprising, in combination, amultiplicity of mirror assemblies each mounted for rotation about itsown axis and with the several axes defining the plane of the screen,means for rotating all of said mirrors in synchronism, each of saidmirror assemblies being mounted for torsional oscillation upon its ownaxis of rotation, and means for maintaining each of said mirrorassemblies in torsional oscillation while in rotation.

'7. In a television system the method of maintaining the aspect ratio ofa television image substantially constant within best viewing limits,which comprises projecting the picture upon a vertical mirror systemsuch that the height of thepicture remains substantially constant as theobserver views it from different distances, rotating the mirror systemto give breadth to the picture, and locating between the observer andthe source of light a lens arranged to magnify in the height of thepicture only in substantially the same ratio as the lateralmagnification introduced by the vertical mirror system, whereby theaspect ratio of the picture remains substantially constant.

8. Television apparatus comprising, in combination, a projector, and amoving mirror screen, the, latter magnifying the projected picture in ahorizontal direction only with change in the observers distance to thescreen, and a lens interposed between the source of light and theobserver affording vertical magnification only of substantially the sameorder as that of the screen, whereby the aspect ratio of the picture ismaintained substantially constant as the observer moves.

9. A television screen comprising twelve triangular shaped, verticallymounted, rotative mirror assemblies, each disploced ten degrees in acounter-clockwise direction from the preceding mirror assembly, eachface of the mirror assembly being the height of the screen andonetwelfth of the width of the screen, and means for rotating the mirrorassemblies to successively bring a mirror face of each assembly intolight reflecting position with respect to an observer.

10. A television screen comprising twelve triangular shaped, verticallymounted, rotative mirror assemblies, each displaced ten degrees in acounter-clockwise direction from the preceding mirror assembly, eachface of the mirror assembly being the height of the screen andone-twelfth of the width of the screen, means for rotating the mirrorassemblies to successively bring a mirror face of each assembly intolight reflecting position with respect to an observer, and means fordecelerating the speed of rotation of each mirror assembly during theperiod when it is in light reflecting position.

11. A television screen comprising twelve triangular shaped, verticallymounted, rotative mirror assemblies, each displaced ten degrees in acounter-clockwise direction from the preceding mirror assembly, eachface of the mirror assembly being the height of the screen andonetwelfth of the width of the screen, means for rotating the mirrorassemblies to successively bring a mirror face of each assembly intolight reflecting position with respect to an observer, means fordecelerating the speed of rotation of each mirror assembly during theperiod when it is in light reflecting position, and accelerating therotation of each mirror assembly when it is not in light reflectingposition, said means comprising a triangular shaped armature mountedupon the mirror assembly and a fixed electromagnet positioned tocooperate with the armature.

12. A television reproducing system comprising a standard containing acathode ray tube suitably energized, a lens positioned to receive thelight projected from said tube and having a substantial magnification inone direction with minor magnification in the cross direction, a screenlocated in front of the lens and spaced therefrom, said screencomprising a plurality of rotating mirrors brought into positionsuccessively so that each reflects only a position of the picture as thesame is projected, but the operation is sufficiently fast that theaction occurs within the limits of the persistence of vision whereby thewhole picture is seen upon the screen simultaneously.

LOUIS W. KOLOZSY.

CERTIFICATE OF CORRECTION, Patent No. 2,1);LL,579. January'l'T, 1959.

LOUIS W KOLOZSY.

It is hereby certified that error appears in the printed specificationof the above numbered patent requiring correction as follows: Page 1,second column,'lines L5 and H strike out the words "and to avoidobjectionable flickering of the pictures" andinsert the same after"presented" and before the period in line 57; page 5, second column,lines 52, 55 and 5h, I the words "which is the natural period of theshaft and its mirror assembly" should be enclosed in parentheses; andthat the said Letters Patent should be read with this correction thereinthat the same may conform to the record of the case in the PatentOffice. I v

Signed andsealed this hthdayof April, A. D. 1959.

Henry Van Arsdale Acting Commissioner of Patents.

CERTIFICATE OF CORRECTION. Patent No. 2,ll lh,579. January'l'Y, 1959.

v LOUIS w. KOLOZSY.

It is hereby certified that error appears in the printed specificationof the above numbered patent requiring correction as follows: Page 1,second 7 columnylines L5 and LLLL, strike out the Words "and to avoidobjectionable flickering of the pictures" and insert the same after"presented" andbefore the period in line 57; page 5, second column,lines 52, 55 and 51 I the words "which is the natural period of theshaft and its mirror assembly" should be enclosed in parentheses; andthat the said Letters Patent should be read with this correction thereinthat the same may conform to the record of the case in the PatentOffice.

Signed andsealed this .hth day of April, A. D. 1959.

Henry Van Arsdale Acting Commissioner of Patents.

